1. Field of the Invention
The present invention relates to valves generally and, more particularly, but not by way of limitation, to a novel fluid flow valve which is particularly useful in applications in which maintaining the purity of the fluid passing through the valve is critical.
2. Background Art
Fluid flow valves are widely used in a variety of applications for controlling the flow of fluids. In some applications, it is critical that the purity of the fluid passing through the valve be maintained. An example of such a application is in the handling of gas in the manufacture of semiconductors.
Known conventional valves for such applications as the latter mentioned above suffer from the disadvantage that the configuration thereof permits impurities to enter the gases passing through them. For example, such conventional valves typically employ, as a sealing member, a relatively large disk or plug constructed of a synthetic material, such as Kel-F. This relatively large volume of synthetic material absorbs moisture which can enter the gas as an impurity. Other impurities, such as other gases, may be similarly absorbed. Furthermore, the sealing disks or plugs of such valves are attached by means of bolts having heads which project into the flow path, disrupting the flow and/or leading to contaminant particle generation. Also, such valves frequently have other such projections or sharp edges which also lend themselves to contaminant particle generation.
A further disadvantage of some known conventional valves is that, when they are moved to a closed position, there is wiping action between sealing members, which wiping action is provided to wipe debris from the faces of the sealing members. This feature, of course, will loosen contaminant particulate matter into the fluid passing through the valves.
Yet another disadvantage of some known conventional valves is that their construction causes them to be larger than would be required with an improved construction.
Accordingly, it is a principal object of the present invention to provide a fluid flow valve in which the volume of the sealing member is minimized.
It is a further object of the invention to provide a fluid flow valve in which there are no projections or sharp edges that can lead to contaminant particle generation.
It is an additional object of the invention to provide a fluid flow valve which does not provide wiping action between sealing members when the valve is being closed.
It is another object of the invention to provide a fluid flow valve which is of such improved construction that it is smaller than conventional valves.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.